Method and device for rapidly measuring laser damage threshold of optical film in real time

Abstract

The invention belongs to the technical field of optical thin film laser damage measurement, discloses a method and a device for quickly measuring a laser damage threshold value of an optical thin film in real time, and relates to a method for determining the laser damage threshold value of the optical thin film based on the change of surface heat reflectivity in a laser damage measurement process. In the laser irradiation process, the temperature of the surface of the thin film is changed, and the heat reflectivity of the surface of the thin film is changed along with the change of the surface temperature; in the laser damage process, the surface temperature of the thin film is sharply increased, so that the heat reflectivity of the surface of the thin film is sharply increased, and the laser damage threshold of the optical thin film is determined by measuring the relative change condition of the reflectivity of the surface of the thin film. According to the invention, the laser damage threshold of the optical thin film can be rapidly determined in real time.

Description

Technical Field

[0001] The invention belongs to the technical field of optical film laser damage measurement, and in particular relates to a method and a device for quickly and real-timely measuring an optical film laser damage threshold. Background Art

[0002] In high-power laser systems, strong light films with high damage thresholds are key components of the entire system, and it is very necessary to determine the laser damage threshold of optical films. At present, the measurement of optical film damage thresholds adopts the international standard ISO11254-1. The basic method is to determine the probability of film damage under different laser energy densities, and then use linear fitting to obtain the damage probability and the corresponding laser energy density to obtain the laser damage threshold.

[0003] Although this method can accurately determine the laser damage threshold of optical films, it is time-consuming because it requires measuring the probability of damage under different laser energy densities, and generally requires a high-precision optical microscope to determine whether the sample is damaged and the probability of damage under a certain laser energy density. In addition, the post-processing data of the damage measurement curve method is relatively cumbersome.

[0004] Through the above analysis, the problems and defects of the prior art are as follows:

[0005] The existing method needs to measure the probability of damage under different laser energy densities, which is time-consuming and generally requires a high-precision optical microscope to determine whether the sample is damaged and the probability of damage under a certain laser energy density. In addition, the post-processing data of the damage measurement curve method is relatively cumbersome. Summary of the invention

[0006] In view of the problems existing in the prior art, the present invention provides a method and device for quickly and real-time measuring the laser damage threshold of an optical film.

[0007] The present invention is implemented as follows: a method for quickly and real-time measuring the laser damage threshold of an optical film comprises:

[0008] Step 1, start the pump laser, collimate the laser, and reasonably adjust the 45-degree turning angle, the half-reflecting half-mirror and the position of the lens so that the laser output by the laser is irradiated vertically on the sample to be tested;

[0009] Step 2, by means of the lens movement adjustment structure, the lens position is adjusted so that the laser output has a suitable spot size on the sample to be tested;

[0010] Step 3, start the detection laser, adjust the optical path so that the detection laser of the detection laser and the pump laser are irradiated on the sample to be tested at a certain angle, start the energy meter and CCD online damage monitoring system, adjust the energy meter and Si avalanche photodiode detector and oscilloscope, set the energy of the pump laser to change gradually from small to large, and measure the thermal reflection signal on the sample surface at the same time.

[0011] Furthermore, as the energy density of the pump laser increases, the intensity of the thermal reflection signal on the sample surface is observed and recorded. When the intensity of the thermal reflectivity signal on the sample surface remains unchanged, the corresponding minimum laser energy is the damage threshold of the optical film.

[0012] Another object of the present invention is to provide a device for quickly and in real time measuring the laser damage threshold of an optical film, comprising:

[0013] A pump laser 1, which is used to excite the sample surface, a laser 2, which is used to collimate the optical path, and a laser 3, which is used to detect the optical path. The lasers 2 and 3 can be the same laser; a sample to be tested located on a computer-controlled moving platform, a Si avalanche photodiode detector for measuring the thermal reflection signal, and an oscilloscope;

[0014] On the output optical path of the pump laser 1, a shutter 3 for controlling the number of output laser pulses, a beam splitter 5, and a laser energy attenuator 4 consisting of a rotatable half-wave plate and a polarizer are arranged.

[0015] Furthermore, the energy attenuator is connected to the computer via a communication line.

[0016] Furthermore, the laser output by the pump laser 1 is attenuated by the attenuator and then irradiated on the sample 15 to be tested on the mobile platform through the focusing lens 10, and an energy meter 5 is arranged on the reflection light path of the spectroscope to measure the laser energy output by the pump laser 1. A 45-degree turning mirror is arranged on the output light path of the laser 2 to realize the collimation of the light path of the pump laser 1.

[0017] Furthermore, a beam splitter 11 is arranged on the output optical path of the laser 3 to split the detection beam into two beams, one of which is passed through a Si avalanche photodiode detector 13 to measure the energy of the reflected detection laser;

[0018] The other beam is reflected by the reflector 12 onto the sample to be tested, and the instantaneous thermal reflection signal on the sample surface is measured by another Si avalanche photodiode detector 14 and recorded by an oscilloscope 16 .

[0019] In combination with the above technical solutions and the technical problems solved, the advantages and positive effects of the technical solutions to be protected by the present invention are as follows:

[0020] First, the advantage of the present invention is that it overcomes the shortcomings of the above-mentioned technologies. It is based on measuring the real-time changes of the thermal reflection signal of the optical film during the laser damage process. When the thermal reflectivity signal intensity of the sample surface remains unchanged, the corresponding minimum laser energy is the damage threshold of the optical film, providing a fast and real-time optical film damage threshold measurement method.

[0021] Second, as auxiliary evidence of the inventiveness of the claims of the present invention, it is also reflected in the following important aspects:

[0022] (1) The technical solution of the present invention fills the technical gap in the industry at home and abroad:

[0023] The present invention proposes a method for determining the damage threshold of an optical film based on the laser damage mechanism of the optical film, filling the gap in the industry in determining the laser damage threshold based on the use of light scattering technology or microscopic imaging technology.

[0024] (2) The technical solution of the present invention overcomes technical prejudice:

[0025] The present invention overcomes the use of light scattering technology or microscopic imaging technology to detect the laser damage threshold of optical elements, and instead proposes a method for determining the damage threshold of optical films based on the laser damage mechanism of optical films. At the same time, the method used in the present invention can assist in analyzing the laser damage mechanism and process of optical films.

[0026] Third, the technical problems solved by the technical solution of the present invention in industrial applications are:

[0027] 1. Low efficiency of laser damage threshold measurement in existing technologies

[0028] Traditional laser damage threshold measurement methods usually require multiple experiments and rely on offline analysis. They are complex and time-consuming to operate, and cannot meet the needs of rapid measurement.

[0029] The present invention can quickly determine the laser damage threshold of the optical film by real-time monitoring of the thermal reflection signal on the sample surface combined with the gradual change in the energy of the pump laser, thereby greatly improving the measurement efficiency.

[0030] 2. The problem of insufficient detection accuracy in existing technologies

[0031] Traditional methods have limited monitoring accuracy for laser energy and sample status, especially in capturing tiny signals and regulating energy density, which can easily lead to measurement errors.

[0032] The present invention adopts an energy meter, a Si avalanche photodiode detector and an oscilloscope to monitor the change of the thermal reflection signal in real time, thereby ensuring the high sensitivity and accuracy of the measurement process and significantly improving the detection accuracy.

[0033] 3. Problems of spot control and energy uniformity in existing technologies

[0034] In the existing technology, it is difficult to accurately adjust the spot size and energy distribution, resulting in uneven laser energy distribution on the sample surface, affecting the reliability of the test results.

[0035] The present invention optimizes the light spot size and realizes uniform energy distribution through the lens movement adjustment structure, thereby effectively avoiding data errors caused by improper light spot control.

[0036] The significant technical progress obtained by the present invention:

[0037] 1. Rapid and real-time detection capabilities

[0038] The present invention can obtain the laser damage threshold of the sample in real time by online thermal reflection signal monitoring and gradually increasing the pump laser energy, without the need for complicated multiple tests and offline analysis. The measurement efficiency is significantly improved compared with traditional methods, meeting the needs of modern industry for efficient detection.

[0039] 2. Improved detection accuracy and reliability

[0040] The present invention uses highly sensitive detection equipment and optimized optical path design to effectively capture the changes in weak thermal reflection signals during laser damage, ensuring the accuracy of damage threshold measurement. In addition, through the gradual regulation and precise recording of energy density, the results are more stable and reliable.

[0041] 3. One-stop solution for optical film performance evaluation

[0042] The present invention integrates multiple functional modules such as optical path adjustment, spot optimization, gradual energy control, and real-time thermal reflection monitoring, providing a one-stop laser damage threshold measurement solution from sample preparation to data output, which significantly reduces the complexity and operation threshold of the measurement system.

[0043] 4. Wide range of industrial applicability

[0044] The present invention is applicable to various types of optical films, including laser lenses, filters, anti-reflection films, etc., and is widely used in the fields of optical material manufacturing, laser equipment research and development, and quality control of high-power optical systems, providing an efficient testing tool for related industries.

[0045] 5. Intelligent measurement to reduce human intervention

[0046] Through automated optical path adjustment, energy control and data acquisition, the present invention realizes intelligent measurement of laser damage threshold, significantly reduces errors caused by human intervention and subjective judgment, and improves the repeatability and consistency of the experiment.

[0047] The present invention solves the problems of inefficiency, insufficient precision and complex operation in existing laser damage threshold measurement technologies. Through real-time thermal reflection monitoring, precise energy regulation and spot optimization, it significantly improves the detection efficiency, accuracy and applicability, and provides an efficient and reliable solution for optical film performance evaluation and laser system quality control. It has important industrial application value and technological progress significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Figure 1 It is a flow chart of a method for quickly and real-time measuring the laser damage threshold of an optical film provided by an embodiment of the present invention.

[0049] Figure 2 It is a structural diagram of a device for rapidly and real-time measuring the laser damage threshold of an optical film provided by an embodiment of the present invention.

[0050] Figure 3 It is a schematic diagram of the laser damage threshold of a sample measured by the method of the present invention provided in an embodiment of the present invention.

[0051] Figure 4 This is a graph of the laser damage threshold of a single-layer HfO2 film determined using ISO11254-1.

[0052] Figure 2 In: 1. Pump laser; 2. Collimated laser; 3. Detection laser; 4. Energy attenuator; 5. Spectroscope; 6. Energy meter; 7. Turning point; 8. Half-reflective and half-mirror lens; 9. Damage judgment device; 10. Focusing lens; 11. Beam splitter; 12. Reflector; 13. Photodiode detector; 14. Photodiode detector; 15. Sample to be tested; 16. Oscilloscope; 17. Computer. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0054] like Figure 1 As shown, a method for quickly and real-time measuring the laser damage threshold of an optical film provided by an embodiment of the present invention includes the following steps:

[0055] S101, start the pump laser, collimate the laser, and reasonably adjust the 45-degree turning angle, the half-reflecting half-mirror and the position of the lens so that the laser output by the laser is irradiated vertically on the sample to be tested;

[0056] S102, adjusting the position of the lens through the movable adjustment structure of the lens so that the laser output by the laser has a suitable spot size on the sample to be tested;

[0057] S103, start the detection laser, adjust the optical path so that the detection laser of the detection laser and the pump laser form a certain angle to irradiate the sample to be tested, start the energy meter and CCD online damage monitoring system, adjust the energy meter and Si avalanche photodiode detector and oscilloscope, set the energy of the pump laser to change gradually from small to large, and measure the thermal reflection signal on the sample surface at the same time.

[0058] The energy density of the pump laser provided in the embodiment of the present invention increases, and the intensity of the thermal reflection signal on the sample surface is observed and recorded. When the intensity of the thermal reflectivity signal on the sample surface remains unchanged, the corresponding minimum laser energy is the damage threshold of the optical film.

[0059] Figure 2 The schematic diagram of the structure of a device capable of quickly and in real time measuring the laser damage threshold of an optical film is shown in the figure. As can be seen from the figure, the present invention provides a device capable of quickly and in real time measuring the laser damage threshold of an optical film, comprising a pump laser 1, which is used to excite the sample surface; a laser 2, which is used to collimate the optical path and assist in monitoring damage, a laser 3 for detecting the optical path, a sample to be tested 15 placed on a mobile platform, two Si avalanche photodiode detectors 13, 14 and an oscilloscope 16. Its composition is:

[0060] On the optical path outputted by the laser 1, a laser pulse control shutter 3, an energy attenuator 4, a beam splitter 5, a half-reflecting half-mirror 8, and a focusing lens 10 are sequentially arranged. The laser outputted by the laser 1 is vertically irradiated on the sample 15 to be tested through the focusing lens 10. An energy meter 6 is arranged on the reflected optical path of the beam splitter 5 to measure the laser energy of the laser 1. In the implementation of the present invention, the laser 1 is a Nd:YAG laser, which adopts electro-optical Q-switching and outputs a base film Gaussian laser with a wavelength of 1064nm. Both lasers 1 and 2 are continuous lasers of 639nm. The energy attenuator 4 is composed of a rotatable half-slope plate and an attenuation plate, which can be controlled by a computer to adjust the laser energy irradiated to the sample surface. The sample 15 to be tested is placed on a moving platform, and the two-dimensional stepping motor controlled by a computer accurately positions the sample test area on this platform, and the accuracy of its single-step movement is 5 microns. The detection laser 3 and the pump laser 1 are irradiated at a certain angle on the sample to be tested 15. The laser is divided into two laser beams by the beam splitter 11. A Si avalanche photodiode detector 13 is set on the reflection light path of the beam splitter 11 to measure the energy of the reflected detection laser. The other beam is reflected by the reflector 12 at a certain angle to the sample surface. The instantaneous thermal reflection signal on the sample surface is detected by the Si avalanche photodiode detector 14 and recorded by the oscilloscope 16. During the measurement process, the CCD online damage judgment device 9 aligns the irradiation point of the pump laser 1 on the sample surface at a certain angle, and relies on the scattering of the laser output by the laser 2 on the sample surface to judge whether damage occurs and the probability of occurrence is compared with the method of the present invention. In the CCD online damage judgment device 9, the energy meter 6 and the oscilloscope are connected to the serial port of the computer 17 through a communication line. In this embodiment, the sample to be tested is a single-layer HfO2 film prepared by electron beam evaporation.

[0061] Measurement process:

[0062] like Figure 3 As shown, the actual use process of the device is described in detail below. First, the sample 15 to be tested is placed on the sample platform to be tested, and then the energy attenuator 4 in the output optical path of the laser 1 is controlled by a computer to control the output energy of the laser. The energy density of the pump laser 1 is set to a fixed value. After the continuous laser with a wavelength of 639nm is adjusted according to the above method, the oscilloscope 16 records the thermal reflection signal of the sample surface detected by the detector 14 in real time, and transmits the data to the computer, increases the energy density of the pump laser, observes and records the intensity of the thermal reflection signal on the sample surface at this time, and when the intensity of the thermal reflectivity signal on the sample surface remains unchanged, the corresponding minimum laser energy is the damage threshold of the optical film. The damage of the sample is judged by the CCD system 9, the damage threshold is determined by the traditional method, and compared with the value obtained by the method of the present invention, the accuracy of the present invention in determining the damage threshold of the optical film can be judged.

[0063] 1. Principle of pump laser excitation and optical path adjustment

[0064] The pump laser 1 is the core component of the device, responsible for providing high-energy laser pulses to excite the surface of the sample to be tested. The output laser adjusts the number of pulses through the shutter 3 to ensure the consistency of the laser pulse parameters for each test. The laser energy attenuator 4 consists of a rotatable half-wave plate and a polarizer, which adjusts the energy of the output laser to adapt to the laser damage threshold range of different samples. The attenuated laser guides the optical path through the beam splitter 5, part of the laser is measured by the energy meter to monitor the stability of the pump laser output, and the remaining laser is focused on the surface of the sample to be tested on the mobile platform through the focusing lens 10 to ensure that the laser energy is concentrated and produces effective excitation.

[0065] 2. Laser optical path alignment and energy distribution principle

[0066] Laser 2 is used to collimate the optical path. By setting a 45-degree turning mirror, the optical path is accurately corrected to ensure that the laser beam output by the pump laser propagates in a straight line and focuses on the sample surface. Laser 3 is used to detect the optical path. The output beam is divided into two beams by a beam splitter 11, one beam is used to measure the energy of the reflected laser, and the other beam continues to reflect and irradiate the surface of the sample to be measured. The joint design of the beam splitter and the turning mirror ensures efficient energy distribution and path optimization of the laser beam, reduces the energy loss of the optical system, and improves the measurement accuracy.

[0067] 3. Measurement and recording principle of thermal reflection signal

[0068] When the laser beam of the pump laser 1 irradiates the sample surface, the sample surface absorbs energy and generates a thermal effect. The instantaneous thermal reflection signal on the sample surface is captured in real time by the Si avalanche photodiode detector 14, and the signal waveform is recorded by the oscilloscope 16. The amplitude and waveform of the reflection signal are directly related to the laser power and the material properties of the sample, and can be used to evaluate the laser damage threshold of the sample surface. By comparing the thermal reflection signals at different laser energy levels, the starting energy of laser damage can be quickly determined.

[0069] 4. Dual detector collaborative measurement principle

[0070] The two beams of light separated from the detection optical path are measured by two Si avalanche photodiode detectors. One beam of light is used to directly measure the reflected energy of the detection laser, and the other beam of light is reflected to the sample surface to measure the thermal reflection signal. The data of the two detectors are collected and transmitted to the oscilloscope at the same time to achieve real-time synchronization and comparative analysis of dual-channel measurement data. This collaborative measurement method improves the accuracy of the correlation evaluation of the reflected energy and the thermal reflection signal.

[0071] 5. Mobile platform and sample position control principle

[0072] The sample to be tested is mounted on a computer-controlled mobile platform, which can automatically move the sample position according to the preset path and the adjustment of the laser light path to ensure that the laser beam acts on the target point. The precise movement of the platform allows multi-point testing on the same sample, thereby drawing a distribution map of the laser damage threshold on the sample surface. Through the centralized control of the computer, the mobile platform works in conjunction with the pump laser and the detection laser to achieve fast and real-time sample testing.

[0073] 6. Data processing and real-time determination principle of laser damage threshold

[0074] The core control system of the device collects data of pump laser output energy, reflected laser energy and sample thermal reflection signal in real time by connecting to an oscilloscope and an energy meter. These data are analyzed by a dedicated algorithm to calculate the energy absorption and thermal effect of the laser on the sample surface, and the laser damage threshold is determined based on the change trend of the reflection signal. When the thermal reflection signal of the sample changes significantly (such as a significant increase in the signal amplitude or a sudden change in the waveform), it indicates the occurrence of laser damage. The system quickly outputs a laser damage threshold report of the sample based on these data.

[0075] The above working principle covers key links such as pump laser excitation, optical path adjustment, thermal reflection signal measurement, dual detector collaboration, mobile platform sample control and data analysis. Through these designs and methods, the device can quickly and accurately measure the laser damage threshold of optical films, providing an efficient tool for the evaluation and application of high-energy laser materials.

[0076] Figure 4 This is a graph of the laser damage threshold of a single-layer HfO2 film determined using ISO11254-1.

[0077] Example 1: Measurement of laser damage threshold of reflective optical films

[0078] Test device structure:

[0079] 1. Pump laser: Nd:YAG laser (wavelength 532nm), pulse width 10ns, repetition frequency 10Hz, peak power adjustable range 50-500mJ.

[0080] 2. Energy attenuator: It is composed of a rotatable half-wave plate and a polarizer, which adjusts the laser energy to adapt to the damage threshold range of different thin film materials.

[0081] 3. Focusing lens: The focal length is 100mm, which is used to focus the pump laser onto the surface of the sample to be tested. The focusing spot diameter is about 200μm.

[0082] 4. Detection optical path: A He-Ne laser (wavelength 633nm) is used as the detection light source, which is divided into two beams by a beam splitter; one beam is used for reflection energy measurement, and the other is used to measure the thermal reflection signal of the sample surface.

[0083] 5. Detectors and recording equipment: Two Si avalanche photodiode detectors are connected to an oscilloscope to collect the reflected laser signal and thermal reflection signal waveforms in real time.

[0084] Testing process:

[0085] 1. Install the reflective optical film sample on a computer-controlled mobile platform, and accurately adjust the sample position through the computer so that the laser spot irradiates the test point.

[0086] 2. Gradually increase the output power of the pump laser, make fine adjustments through the energy attenuator, and record the changes in the thermal reflection signal under different laser energies.

[0087] 3. Determine the critical point when the laser energy reaches the film damage threshold through the waveform changes of the reflected signal and the thermal reflected signal.

[0088] 4. After the test is completed, the multi-point test results are plotted as an optical film damage threshold distribution diagram to evaluate the laser damage resistance of the film material.

[0089] Example 2: Measurement of laser damage threshold of transmissive optical films

[0090] Test device structure:

[0091] 1. Pump laser: Use Ti: Sapphire femtosecond laser (wavelength 800nm), pulse width 50fs, peak power 10-100mJ.

[0092] 2. Energy attenuator: includes attenuation plate group and mechanical shutter to ensure that the laser output energy is stable and adjustable.

[0093] 3. Sample fixing platform: The transmissive optical film is installed in the sample frame on the platform, which can achieve ±5° inclination adjustment to facilitate optical path alignment.

[0094] 4. Detection optical path: Use a spectroscope to split the detection laser into two beams, one beam directly passes through the sample to measure the transmission signal, and the other beam is used for the reflection optical path to measure the thermal signal on the sample surface.

[0095] 5. Detector and data acquisition equipment: InGaAs photodetector and Si avalanche photodiode detector are configured respectively, and the transmission signal and thermal signal are recorded by oscilloscope respectively.

[0096] Testing process:

[0097] 1. Install the transmissive optical film and adjust the inclination of the sample frame so that the laser light path passes through the sample vertically.

[0098] 2. Adjust the power output of the pump laser, gradually increase the laser energy, and record the changes in the transmission signal and thermal reflection signal through the detection optical path.

[0099] 3. When the amplitude of the thermal reflection signal increases significantly and the transmission signal drops suddenly, it is judged that the sample has been damaged by laser and the laser energy value at this time is recorded.

[0100] 4. Perform multi-point measurements on different areas of the film through a mobile platform to analyze the laser damage threshold distribution of the transmissive optical film at different locations.

[0101] Notable features of both embodiments:

[0102] 1. Embodiment 1 is for reflective films and uses the mutation characteristics of thermal reflection signals to accurately determine the damage threshold; Embodiment 2 combines the changes in transmission signals and is suitable for evaluating the damage performance of transmission films.

[0103] 2. Both embodiments use dual detectors and a computer-controlled mobile platform to ensure the efficiency of multi-point measurement and the accuracy of data, providing a comprehensive evaluation tool for the laser damage performance of optical films.

[0104] The present invention first starts the pump laser and the collimation laser, and by properly adjusting the positions of the 45-degree turning mirror, the half-reflecting half-mirror and the lens, ensures that the laser beam output by the laser is vertically irradiated on the surface of the sample to be tested. This optical path adjustment process achieves high-quality beam control through precision optical elements, providing precise laser irradiation conditions for subsequent measurement of the damage threshold of optical thin films. In addition, vertically incident lasers can minimize optical path errors and improve the repeatability and reliability of the experiment.

[0105] Through the lens movement adjustment structure, the lens position is adjusted to control the laser spot size on the sample surface to meet the experimental requirements. Reasonable selection of spot size can ensure uniform laser energy distribution on the sample surface and avoid local overload or data error caused by too large or too small spot. This step ensures the accuracy and uniformity of laser irradiation and is a key link in accurately measuring the laser damage threshold of optical films.

[0106] Start the detection laser so that the detection laser and the pump laser form a certain angle to irradiate the sample. Use the linkage configuration of energy meter, CCD online damage monitoring system, Si avalanche photodiode detector and oscilloscope to monitor the thermal reflection signal on the sample surface in real time. By adjusting the optical path, ensure the matching and stability of the detection optical path and the pump laser optical path, so as to achieve high-sensitivity detection of changes in the thermal reflectivity of the sample. The design of the detection optical path can quickly capture the tiny changes in the thermal reflection signal of the sample after being acted on by the laser, providing real-time data support for damage threshold measurement.

[0107] By gradually increasing the energy density of the pump laser, the thermal reflection signal on the sample surface is observed in real time. When the laser energy increases to a certain value, the intensity of the thermal reflection signal on the sample surface stops changing, indicating that the sample has reached the damage threshold. The minimum laser energy recorded at this time is the damage threshold of the optical film. Through this method, combined with precise energy control and thermal reflection signal monitoring, the present invention can quickly and real-time determine the laser damage threshold of the optical film, providing an efficient and reliable detection method for the performance evaluation of thin film materials.

[0108] The above description is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by any technician familiar with the technical field within the technical scope disclosed by the present invention and within the spirit and principle of the present invention should be covered by the protection scope of the present invention.

Claims

1. A device for rapid and real-time measurement of laser damage threshold of optical thin films, characterized in that: include: A pump laser is used to excite the surface of the sample to be tested; An energy attenuator, including a rotatable half-wave plate and a polarizer, for adjusting the laser energy output by the pump laser; A beam splitter is used to separate the optical path of the pump laser. One part of the optical path is used for sample excitation, and the other part of the optical path is connected to an energy meter to measure the laser energy. A focusing lens, used to focus the pump laser onto the surface of the sample to be tested; The computer-controlled mobile platform on which the sample to be tested is mounted is used to accurately locate the sample test point.

2. The device according to claim 1, characterized in that Also includes: A laser is used for collimating the optical path, and the collimating optical path adjusts the laser direction through a 45-degree turning mirror; A beam splitter is used to split the detection laser into two beams, which are respectively directed to a reflection energy measurement path and a thermal reflection signal measurement path.

3. The device according to claim 1, characterized in that The reflected energy measurement path includes: Si avalanche photodiode detector to measure the reflected energy of the detection laser; An oscilloscope, connected to the detector, is used to record the energy data of the reflected laser signal.

4. The device according to claim 1, characterized in that The thermal reflection signal measurement path includes: Si avalanche photodiode detector, used to measure the instantaneous thermal reflection signal on the surface of the sample to be tested; A reflector, used to guide the detection laser to the surface of the sample to be tested; An oscilloscope, connected to the detector, is used to record the instantaneous thermal reflection signal of the sample surface.

5. The device according to claim 1, characterized in that The energy attenuator is connected to a computer via a communication line. The computer is used to control the dynamic adjustment of laser energy and work in coordination with the mobile platform to achieve multi-point testing.

6. The device according to claim 1, characterized in that The mobile platform comprises: A computer control module is used to accurately move the position of the sample to be tested according to a preset path; Sample fixing fixture, used to fix the sample to ensure the test stability; Adjustable support frame, used to adjust the vertical or tilt angle between the sample and the laser beam path.

7. A method for rapid and real-time measurement of laser damage threshold of optical thin films, characterized in that: The following steps are involved: Step 1, start the pump laser, collimate the laser, and reasonably adjust the 45-degree turning angle, the half-reflecting half-mirror and the position of the lens so that the laser output by the laser is irradiated vertically on the sample to be tested; Step 2, by means of the lens movement adjustment structure, the lens position is adjusted so that the laser output has a suitable spot size on the sample to be tested; Step 3, start the detection laser, adjust the optical path so that the detection laser of the detection laser and the pump laser are irradiated on the sample to be tested at a certain angle, start the energy meter and CCD online damage monitoring system, adjust the energy meter and Si avalanche photodiode detector and oscilloscope, set the energy of the pump laser to change gradually from small to large, and measure the thermal reflection signal on the sample surface at the same time.

8. The method for rapid and real-time measurement of laser damage threshold of optical thin films as claimed in claim 7, characterized in that: As the energy density of the pump laser increases, the intensity of the thermal reflection signal on the sample surface is observed and recorded. When the intensity of the thermal reflectivity signal on the sample surface remains unchanged, the corresponding minimum laser energy is the damage threshold of the optical film.

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